JP2007163811A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device and an image forming apparatus that improve image quality by reducing localization of a developer in the developing device. <P>SOLUTION: A top surface portion of a partition wall 7 which is a bottom part of a first chamber 3 is provided obliquely to ascend in a developer conveying direction in the first chamber 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a developing device for forming a visible image by attaching a developer to an electrostatic image formed on an image bearing member, and an electrophotographic method or an electrostatic device equipped with such a developing device. The present invention relates to an image forming apparatus such as a copying machine or a laser beam printer using a recording method.

  In an image forming apparatus such as a copying machine using an electrophotographic system, a developer is attached to an electrostatic image formed on an image carrier such as a photosensitive drum to form a visible image. As a developing device according to the prior art used for such development, one using a two-component developer containing toner and carrier is known. An example is shown in FIG. FIG. 8 is a schematic cross-sectional view of a conventional developing device.

  In the developing device 101 using the two-component developer shown in FIG. 8, two first conveying screws 105 and two second conveying screws 106 that convey the two-component developer while stirring are arranged in the horizontal direction. There are many things. The first conveying screw 105 supplies a developer to a developer carrying member (hereinafter referred to as “developing sleeve”) 108 and collects the developer after passing through the developing area A facing the photosensitive drum 110. Used for.

  The second conveying screw 106 is used for mixing and stirring the developer collected from the developing sleeve 108 and the newly supplied developer.

  On the other hand, in recent years, in an image forming apparatus using an electrophotographic system such as a copying machine or a printer, there is an increasing demand for downsizing of the apparatus main body in order to achieve space saving. In particular, in a full-color image forming apparatus, since a plurality of developing devices are used, there is a strong demand for downsizing.

  Thus, for example, developing devices as disclosed in Patent Document 1 and Patent Document 2 are known.

  First, a conventional developing device disclosed in Patent Document 1 will be described with reference to FIGS.

  9 shows a transverse section perpendicular to the axial direction of the developing sleeve 108 and the conveying screws 105 and 106 in the developing device 101, and FIG. 10 shows a longitudinal section in the axial direction.

  The vertical stirring type developing device 101 shown in FIG. 9 is characterized in that two transport screws 105 and 106 for stirring and transporting the developer are arranged vertically.

  More specifically, the developing device 101 includes a developing container 102 that stores a developer, and has a developing sleeve 108 at an opening facing the photosensitive drum 110 of the developing container 102. A developing chamber 103 and a stirring chamber 104 defined by a partition wall 107 are formed vertically on the opposite side of the opening in the developing container 102. In the developing chamber 103 and the agitating chamber 104, a first conveying screw 105 and a second conveying screw 106 are respectively installed as a developer agitating / conveying means.

  The first conveying screw 105 conveys the developer in the developing chamber 103. The second conveying screw 106 agitates new toner supplied into the agitating chamber 104 from the toner supply port on the upstream side of the second conveying screw 106 and the developer already in the agitating chamber 104. Then, the toner density of the developer is made uniform.

  As described above, the vertical stirring type developing device 101 shown in FIG. 9 has the advantage that the space occupied in the horizontal direction can be small because the developing chamber 103 and the stirring chamber 104 are arranged in the vertical direction. There is. Therefore, for example, a color image forming apparatus such as a tandem system in which a plurality of developing devices are mounted in parallel in the horizontal direction can be downsized.

  Further, this vertical stirring type developing device has the following advantages.

  That is, as shown in FIG. 9, the developer in the developing chamber 103 is carried on the developing sleeve 108 and is transported to the developing area A for use in development. Thereafter, the developer that has not been subjected to development in the development region A is not collected on the developing chamber 103 side but is collected on the stirring chamber 104 side as the developing sleeve 108 rotates. Therefore, only the developer that has been sufficiently stirred in the stirring chamber 104 is always present in the developing chamber 103.

Accordingly, the developing sleeve 108 is always supplied with a developer having a uniform density, and image unevenness in the thrust direction (image unevenness caused by insufficient stirring) and density difference (density difference caused by insufficient stirring). A uniform image can be obtained.
JP-A-5-333691 JP-A-6-51634

  However, as described above, the vertical stirring type developing device 101 as described above has the advantage of being suitable for downsizing, and the advantage that the developer that has not been developed can be returned to the stirring chamber, The following problems exist.

  That is, as shown in FIG. 10, the first conveying screw 105 is disposed substantially parallel to the bottom of the developing chamber 103 along the axial direction of the developing sleeve 108, and rotates to develop the developing chamber 103. The agent is conveyed in one direction along the axial direction.

  The second conveying screw 106 is disposed at the bottom of the agitating chamber 104 substantially in parallel with the first conveying screw 105, and the developer in the agitating chamber 104 is opposite to the conveying direction of the first conveying screw 105. Transport to.

  In this way, the developer is transported by the rotation of the first transport screw 105 and the second transport screw 106, so that the developer passes through the openings 111 and 112 at both ends of the partition wall 107, and the developing chamber 103 and the stirring chamber 104. Cycled between.

  Incidentally, in such a developing device 101, the developing chamber 103 and the stirring chamber 104 are arranged in the vertical direction. Therefore, as shown in FIG. 10, the developer from the developing chamber 103 to the stirring chamber 104 moves from the top to the bottom, and the developer from the stirring chamber 104 to the developing chamber 103 moves from the bottom to the top.

  In particular, the developer is delivered from the agitating chamber 104 to the developing chamber 103 so as to be pushed up from below by the pressure of the developer accumulated at the end. The developer circulation path at this time is shown in FIG.

  As shown in FIG. 11, not all of the developer transferred from the stirring chamber 104 to the developing chamber 103 reaches the downstream end of the first conveying screw 105 in the developing chamber 103. There is a component that is supplied to the developing sleeve 108 on the way and is collected in the stirring chamber 104 after passing through the developing region. The path of this component is indicated by arrow a in FIG.

  The developer is transferred to the developing sleeve 108 over substantially the entire width of the developing sleeve 108. For this reason, as shown in FIG. 10, the amount of developer conveyed by the first conveying screw 105 in the developing chamber 103 tends to gradually decrease from the upstream end toward the downstream end. On the other hand, in the stirring chamber 104, the amount of developer conveyed by the second conveying screw 106 tends to gradually increase from the upstream end to the downstream end. That is, there is a deviation in the developer distribution in the developing device 101.

  In particular, when the developer amount in the developing chamber 103 is shifted, the supply to the developing sleeve 108 becomes uneven, and the density of the image formed due to this non-uniformity varies in the axial direction of the developing sleeve 108. That is, on the upstream side of the developing chamber conveyance path where the amount of developer is large, the amount of developer supplied to the developing sleeve 108 is stable and the image density is constant. However, on the downstream side of the developing chamber conveyance path with a small amount of developer, the amount of developer supplied to the developing sleeve 108 is small, resulting in uneven density in the image and image defects.

  FIG. 12 shows a developing device of a type having a developing chamber and a stirring chamber and having two developing sleeves arranged like the developing device 101 of FIG. In this type of developing device, ideally, the developer supplied from the developing chamber 103 to the upper sleeve 108a is transferred from the upper sleeve 108a to the lower sleeve 108b and peeled off from the lower sleeve 108b. Is supplied to the stirring chamber 104. Thereafter, the developer supplied to the developing chamber 103 through the same path as described above is supplied again to the upper sleeve 108 a in the developing chamber 103.

  However, also in the developing device 101 of the type shown in FIG. 12, when the stirrer chamber 104 is shifted as described above, the following state occurs. When the developer surface in the stirring chamber 104 is high, that is, downstream of the stirring chamber conveyance path, the developer is supplied from the stirring chamber 104 to the lower sleeve 108b in the direction of the arrow indicated by arrow A in FIG. There is.

  Considering the ideal developer flow described above, when the flow of the arrow A occurs, the developer is excessively supplied to the lower sleeve 108b only at that portion, which may cause density unevenness in the image and image defects. is there.

  As a countermeasure against the above problem, as in the technique disclosed in Patent Document 1, the developer conveying ability of the first and second conveying screws 105 and 106 is made sufficiently larger than the supply amount to the developing sleeve 108a. It is also conceivable to make the offset effect relatively small. However, if the developer conveyance amount is increased by increasing the rotation speed of the conveyance screws 105 and 106, there is a problem that stress cannot be increased too much because there is an increase in stress on the developer and an increase in rotational torque.

  Further, even when the conveying speed is increased by improving the pitch and shape of the conveying screw, the upper limit of the conveying speed is limited, so that it is not effective when the degree of deviation is severe.

  As another countermeasure against the above problem, there is a technique disclosed in Patent Document 2. That is, it is the structure shown with the dashed-dotted line in FIG. In this configuration, a third conveying screw 113 is provided between the developing sleeve 108 and the second conveying screw 106 provided in the stirring chamber 104 to alleviate the deviation. However, in this case, there is a problem that the configuration of the developing device becomes complicated, which may cause an increase in cost.

  The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to provide a developing device and an image that improve the image quality by reducing the deviation of the developer in the developing device. It is to provide a forming apparatus.

The above object is achieved by the developing device and the image forming apparatus according to the present invention. In summary, according to the first aspect of the present invention, at least one or more rotatable developer carrier for carrying and developing the developer in the development region,
A first chamber extending along a rotation axis direction of the developer carrying member and supplying a developer to the developer carrying member;
A second chamber disposed adjacent to and below the first chamber, and partitioned by a partition wall from the first chamber;
With
A first communication part and a second communication part for communicating the first chamber and the second chamber are provided in the vicinity of both ends of the partition wall in the rotation axis direction, respectively.
The developer conveying member provided in the first chamber and the second chamber conveys the developer from the second chamber to the first chamber via the first communicating portion, and the second communicating portion. In the developing device for circulating the developer between the first chamber and the second chamber by dropping the developer from the first chamber to the second chamber via
A developing device is provided, wherein an upper surface portion of the partition wall serving as a bottom portion of the first chamber is provided to be inclined so as to rise in a developer transport direction in the first chamber.

According to a second aspect of the present invention, an image carrier on which an electrostatic image is formed, and a developing device for developing the electrostatic image on the image carrier with a developer applied to a development region are provided. In the image forming apparatus,
An image forming apparatus is provided in which the developing device is a developing device having the above-described configuration.

  According to the present invention, the amount of developer in the thrust direction and the deviation of the developer surface can be reduced, and the image quality can be improved.

  Exemplary embodiments of the present invention will be described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. Absent.

  In the following description, an image forming apparatus that forms a full-color image will be described as an example of an image forming apparatus. However, an image forming apparatus to which the developing device of the present invention is applied is described as such. Needless to say, it is not limited to a device.

Example 1
An image forming apparatus and a developing apparatus according to an embodiment of the present invention will be described with reference to FIGS.

  First, schematic configurations of the image forming apparatus and the developing apparatus will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic sectional view of an image forming apparatus according to an embodiment of the present invention. 2 is a transverse sectional view of an embodiment of the developing device according to the present invention, and FIG. 3 is a longitudinal sectional view of the developing device.

  FIG. 1 schematically shows a drum-shaped electrophotographic photosensitive member (hereinafter referred to as “photosensitive drum”) as an image carrier provided in the image forming apparatus main body and a developing device.

  As shown in FIG. 1, a full-color image forming apparatus 100 is known that includes a plurality of image forming stations P. In this embodiment, for example, image forming stations P (PY, PM, PC, PK) are provided for four colors of yellow (Y), magenta (M), cyan (C), and black (K). FIG. 1 mainly shows a developing device portion of one image forming station P.

  The image forming stations P (PY, PM, PC, PK) have almost the same configuration. In a full-color image, yellow (Y), magenta (M), cyan (C), and black (K) respectively. Form an image.

  In the following description, if the developing device 1 is used, the developing device 1Y, the developing device 1M, the developing device 1C, and the developing device 1K in each of the stations P (PY, PM, PC, PK) of Y, M, C, and K are shared. To point to. In FIG. 1, Y, M, C, and K are added to the reference numerals of the respective components, but they are omitted in the following description.

  First, the configuration and operation of the entire image forming apparatus will be described with reference to FIG.

  The photosensitive drum 10 that is an image carrier is rotatably provided, and the surface of the photosensitive drum 10 is uniformly charged by a primary charger 21 that is a charging unit. Thereafter, the surface of the uniformly charged photosensitive drum 10 is exposed to light modulated in accordance with an information signal by a light emitting element 22 as a latent image forming unit such as a laser to form an electrostatic latent image. . The electrostatic latent image formed in this way is visualized as a toner image by the developing device 1.

  Next, the visible image is transferred to a transfer paper 27 as a transfer material conveyed by a transfer paper conveyance sheet 24 as a transfer material carrier by a transfer charger 23 as a transfer means. The toner image transferred onto the transfer paper 27 is fixed by the fixing device 25 to obtain a permanent image. Further, the transfer residual toner on the photosensitive drum 10 is removed by the cleaning device 26. Further, the toner consumed in the image formation is supplied from the toner supply tank 20.

  Next, the operation of the developing device 1 will be described with reference to FIGS.

  The developing device 1 according to this embodiment includes a developing container 2 that stores a two-component developer including a nonmagnetic toner and a magnetic carrier. In the developing container 2, a developing sleeve 8 as a developer carrying member for applying a developer to the developing region and performing development, and a panning for regulating the ears of the developer carried on the developing sleeve 8. And a member 9. A substantially central portion in the developing container 2 is vertically divided into a developing chamber 3 and a stirring chamber 4 by a partition wall 7 extending in a direction perpendicular to the paper surface in FIG. 1, that is, in a rotating shaft direction of the developing sleeve 8. . The developer is accommodated in the developing chamber 3 and the stirring chamber 4.

  In the developing chamber 3 and the agitating chamber 4, a first conveying screw 5 and a second conveying screw 6 are arranged as developer agitating / conveying members, respectively. Although not limited to this, in the present embodiment, the first conveying screw 5 and the second conveying screw 6 rotate in the direction of the arrow.

  The first conveying screw 5 is disposed substantially parallel to the bottom of the developing chamber 3 along the rotation axis direction of the developing sleeve 8, and rotates to remove the developer in the developing chamber 3 along the axial direction. Transport in the direction.

  The second conveying screw 6 is disposed at the bottom of the stirring chamber 4 substantially in parallel with the first conveying screw 5, and the developer in the stirring chamber 4 is opposite to the conveying direction of the first conveying screw 5. Transport to.

  In this way, the developer is transported by the rotation of the first and second transport screws 5, 6, so that the developer communicates with the opening 11 as the first communication portion provided at both ends in the longitudinal direction of the partition wall 7 and the second communication. It is circulated between the developing chamber 3 and the stirring chamber 4 through the opening 12 as a portion.

  Further, an opening 2a is provided at a position facing the photosensitive drum 10 of the developing container 2 (that is, the developing area A), and the developing sleeve 8 is partially exposed to the opening 2a in the direction of the photosensitive drum 10. It is rotatably arranged. The developing sleeve 8 is made of a nonmagnetic material, and a magnet roller 80 as a magnetic field means is installed in a non-rotating state inside the developing sleeve 8. The magnet roller 80 has a developing pole S1 and magnetic poles N1, S2, N2, and N3 that convey the developer.

  With the above configuration, the developing sleeve 8 rotates in the direction indicated by the arrow in the drawing, that is, in the developing area A in the same direction as the photosensitive drum 10 during development. The developer carried on the developing sleeve 8 is regulated in layer thickness by cutting off the magnetic brush by the ear cutting member 9 as a developer layer thickness regulating member attached to the developing container 2. The two-component developer whose layer thickness is regulated is carried by the developing sleeve 8 and conveyed to the developing area A facing the photosensitive drum 10, and the developer is applied to the electrostatic image formed on the photosensitive drum 10. Supply and develop electrostatic image. At this time, in order to improve the development efficiency (that is, the application rate of toner to the electrostatic image), a development bias voltage in which a DC voltage and an AC voltage are superimposed is applied to the development sleeve 8 from a power source.

  The ear cutting member 9 is made of a non-magnetic member such as aluminum, and is disposed on the upstream side of the photosensitive drum 10 in the rotation direction of the developing sleeve 8 so as to face the magnetic pole S <b> 2 of the magnet roller 80. Then, the developer (both non-magnetic toner and magnetic carrier) passes between the tip portion of the spike cutting member 9 and the developing sleeve 8 and is sent to the developing area A.

  The amount of developer conveyed to the development area A is regulated by adjusting the gap between the ear cutting member 9 and the surface of the developing sleeve 8 to regulate the amount of cutting of the developer magnetic brush carried on the developing sleeve 8. Is adjusted.

  The first conveying screw 5 is disposed substantially parallel to the bottom of the developing chamber 3 along the axial direction (developing width direction) of the developing sleeve 8. In this embodiment, a screw structure is adopted in which blade members made of a nonmagnetic material are provided in a spiral shape around a rotating shaft made of a ferromagnetic material. The developer in the developing chamber 3 is conveyed along the axial direction of the developing sleeve 8 at the bottom of the developing chamber 3 by the rotation of the first conveying screw 5.

  Similarly to the first conveying screw 5, the second conveying screw 6 adopts a screw structure in which a blade member is provided in a spiral shape around the rotation axis in a direction opposite to the first conveying screw 5. The second conveying screw 6 is disposed at the bottom of the stirring chamber 4 substantially in parallel with the first conveying screw 5 and rotates in the same direction as the first conveying screw 5 to remove the developer in the stirring chamber 4. The first conveying screw 5 is conveyed in a direction opposite to the conveying direction.

  In this way, the developer is circulated between the developing chamber 3 and the stirring chamber 4 through the openings 11 and 12 at both ends of the partition wall 7 by the rotation of the first and second conveying screws 5 and 6. .

  Incidentally, since the developing chamber 3 and the stirring chamber 4 are arranged in the vertical direction in the developing device 1 of the present embodiment, the developer from the developing chamber 3 to the stirring chamber 4 flows from above through the opening 12. The developer falls downward, and the developer from the stirring chamber 4 to the developing chamber 3 flows from the bottom to the top through the opening 11. In particular, the developer is delivered from the agitating chamber 4 to the developing chamber 3 so as to be pushed up from below by the pressure of the developer accumulated at the end.

  At this time, as described in the prior art, not all of the developer transferred from the stirring chamber 4 to the developing chamber 3 reaches the downstream end of the first conveying screw 5 in the developing chamber 3. The developer is supplied to the developing sleeve 8 on the way, and there is a component that is recovered in the stirring chamber 4 after passing through the developing region A. The developer is transferred to the developing sleeve 8 between the longitudinal ends 81 and 82 of the developing sleeve 8, that is, over almost the entire longitudinal developing area WA of the developing sleeve 8.

  For this reason, the amount of developer transported by the first transport screw 5 in the developing chamber 3 tends to gradually decrease from the upstream end toward the downstream end. On the other hand, the amount of developer conveyed by the second conveying screw 6 in the stirring chamber 4 tends to gradually increase from the upstream end to the downstream end.

  That is, there is a deviation in the developer distribution in the developing device. In particular, when the amount of developer in the developing chamber 3 is shifted to the side, the supply to the developing sleeve 8 becomes uneven, and the density of the image formed due to this non-uniformity differs in the axial direction of the developing sleeve 8. Image defects occur.

  Therefore, in the present embodiment, the partition wall 7 that partitions the developing chamber 3 and the stirring chamber 4 is inclined so as to rise toward the downstream side in the developer conveying direction by the first conveying screw 5 in the developing chamber 3. The deviation of the developer distribution can be reduced. This point will be described in more detail with reference to FIG. FIG. 3A is a schematic sectional view of a conventional developing device, and FIG. 3B is a schematic sectional view of the developing device according to the first embodiment of the present invention.

  In this embodiment (FIG. 3B), the circulation of the developer in the developing container is different from that in the conventional example (FIG. 3A) as follows.

  In other words, in the developing device of the present embodiment, the partition wall 7 is provided so as to be inclined toward the downstream side in the developer transport direction in the developing chamber 3. This inclination constitutes a mechanism for suppressing the deviation of the developer distribution.

  This embodiment having such a configuration is characterized in that the developer surface TS of the transport path in the developing chamber 3 is higher than in the conventional example.

  As described above, the developer transferred from the stirring chamber 4 is conveyed while being gradually transferred to the developing sleeve 8 by the first conveying screw 5 in the developing chamber 3 and falls through the opening 12 at the downstream end. Then, it circulates to the stirring chamber 4.

  Here, in the conventional developing device, as shown in FIG. 3A, almost all of the developer transported to the downstream end of the transport path in the developing chamber 3 passes through the opening 12 to the stirring chamber 4. And falling. For this reason, the developer amount decreases on the downstream side in the developing chamber 3, and the developer amount in the developing chamber 3 is shifted.

  On the other hand, in this embodiment, as shown in FIG. 3B, the partition wall 7 between the developing chamber 3 and the stirring chamber 4 is provided with an inclination that rises in the developer conveying direction of the developing chamber 3. Yes. For this reason, the conveying force is received by the first conveying screw 5 in the developing chamber 3, and the conveying force is received in the opposite direction of the conveying screw 5 by the inclination of the partition wall 7. Further, the position of the downstream end of the developing chamber also rises with respect to the sleeve 8, and the developer surface TS of the developer conveyed to the downstream side of the developing chamber rises compared to the conventional case, and the amount of developer in the thrust is increased. Distribution deviation is also reduced.

  Therefore, according to the present embodiment, the developer surface TS in the developing chamber 3 of the developer conveyed from the developing chamber 3 to the stirring chamber 4 through the opening 12 is raised as compared with the conventional one, and the developer amount on the downstream side is increased. Can be secured. Therefore, as shown in FIG. 3B, it is possible to reduce the deviation of the distribution of the developer amount in the developing chamber 3.

  The degree of deviation of the developer surface TS can be adjusted by the degree of inclination of the partition wall 7 with respect to the horizontal, that is, the inclination angle (α). If the inclination angle (α) is small, the effect of the present invention is small, and if it is too large, the transportability in the developing chamber 3 is impaired, which is not preferable.

According to the study by the present inventors, the inclination angle (α) is preferably between 1 and 15 °. More preferably, as shown in FIGS. 3B and 3C, the inclination angle (α) is more preferably equal to or smaller than the angle (β). The angle (beta), by connecting the axial center line L1 passing through the center O ₁ -O ₁ of the sleeve 8 to be used, the center O ₁ of the maximum outer diameter portion and the sleeve 8 at both ends 81, 82 of the sleeve 8 is formed Is an angle (β) formed by the diagonal line L2. This is because if the inclination angle (α) is larger than the angle (β), the transportability on the agitating chamber side is impaired, the intake of the developer peeled off from the sleeve is impaired, and the developer may be overflowed. Because there is.

  In the present embodiment, both ends 81 and 82 of the sleeve 8 do not necessarily mean the longitudinal end surface portion of the developing sleeve 8, but, as described above, the longitudinal developer carrying maximum area WA of the developing sleeve 8. It means the end face that prescribes. The longitudinal developer carrying maximum region is the maximum length in the longitudinal direction in which the developer can be carried and conveyed.

  As understood with reference to FIGS. 2 and 3, the following configuration is provided to further enhance the effect of the developing device according to the present embodiment. That is, the height position H1 of the developer surface TS with respect to the downstream end surface 81 of the developing sleeve 8 in the developer transport direction in the developing chamber 3 is preferably located above the center line L1 of the developing sleeve 8.

  Usually, the developer surface TS in the developing chamber 3 is inclined in the cross-sectional direction of the developing chamber 3 by the rotation of the first conveying screw 5 as shown in FIG. Therefore, in this embodiment, the height position H1 is a position in contact with the developing sleeve 8 at the position of the downstream end face 81 of the developing sleeve 8.

  Further, it is more preferable that the height position h1 of the partition wall 7 with respect to the end surface 81 of the developing sleeve 8 is located above the center line L1 of the sleeve 8 and below the upper outer peripheral position OS of the developing sleeve 8. Result. This is because when the position h1 is positioned above the position OS, the supply of the developer to the developing sleeve is impaired, and the developer on the sleeve is biased in the thrust direction, resulting in image defects (density unevenness). Because there is a fear.

  Further, to enhance the effect of the developing device according to the present embodiment, the height position H2 of the developer surface TS with respect to the downstream end surface 82 of the developing sleeve 8 in the developer transport direction in the stirring chamber 4 is It is preferable to be located below the center line L1.

  Normally, the developer surface TS in the stirring chamber 4 is also inclined in the cross-sectional direction of the stirring chamber 4 by the rotation of the second conveying screw 6 as shown in FIG. Therefore, in the present embodiment, the height position H2 is the highest position at the downstream end face 82 position of the developing sleeve 8.

  Further, it is more preferable that the height position h2 of the partition wall 7 with respect to the end face 82 of the developing sleeve 8 is located below the center line L1 of the sleeve 8. This is because the developer in the agitation chamber is less likely to be attracted to the magnetic pole in the developing sleeve, thereby making it possible to prevent the developer bias on the developing sleeve from occurring.

  The height positions h1 and h2 of the partition wall 7 are curved in a cross-sectional shape so that the bottom surface of the partition wall 7 partially surrounds the lower part of the first conveying screw 5 as shown in FIG. In this case, it means the upper surface 7a and the lower surface 7b of the bottom surface of the partition wall that is the lowest.

  In this way, the deviation of the developer in the developing device is reduced, and the supply of the developer to the developing sleeve 8 is uniformly performed in the axial direction, thereby preventing the occurrence of image defects such as density unevenness. It is possible to provide a developing device that can be used.

Example 2
FIG. 4 shows a second embodiment of the present invention. In the first embodiment, as the mechanism for controlling the developer surface and the developer amount distribution in the developer chamber 3 of the developer, the configuration in the case where the partition wall 7 is inclined is shown.

  In the present embodiment, the partition wall 7 is inclined and the first conveying screw 5 is also inclined along the partition wall 7. Since other configurations and operations are the same as those in the first embodiment, the same components are denoted by the same reference numerals and description thereof is omitted.

  Next, with reference to FIG. 4, a configuration for regulating the developer surface distribution in the developer chamber 3 and the developer amount on the thrust according to the present embodiment will be described. FIG. 4A shows a conventional example, and FIG. 4B is a schematic cross-sectional view of the developing device of this embodiment.

  The developing device of this embodiment is characterized in that the conveying screw 5 is arranged substantially in parallel with the partition wall 7.

  According to this embodiment, on the upstream side in the developing chamber conveyance direction, it becomes possible to quickly convey the developer that has risen due to the pressure from the stirring chamber 4, and it will be understood by comparing FIGS. 4 (a) and 4 (b). As a result, the developer surface TSu on the upstream side of the developing chamber can be lowered.

  Further, since the partition wall 7 is provided so as to rise with respect to the developer conveyance direction in the developing chamber 3, the conveyance force is received on the opposite side to the conveyance direction by gravity. At the same time, since the end surface 81 on the downstream side in the developing chamber transport direction is raised with respect to the sleeve 8, the developer surface TSd of the developer transported to the downstream side of the developing chamber is raised compared to the conventional case, and the thrust surface is increased. The deviation of the developer amount distribution in the toner is also reduced.

  Also in the developing device thus obtained, the deviation in the distribution of the developer amount in the developing device is reduced, and the developer is uniformly supplied to the developing sleeve 8 in the axial direction. It is possible to prevent the occurrence of image defects such as.

Example 3
FIG. 5 shows a third embodiment of the present invention.

  In the first embodiment, as the mechanism for controlling the developer surface and the developer amount distribution in the developer chamber 3 of the developer, the configuration in the case where the partition wall 7 is inclined is shown.

  In the present embodiment, a configuration in which the distribution of the developer amount in the developer surface and the thrust surface in the developer chamber 3 is regulated by inclining the upper surface 7a of the partition wall 7 will be described.

  Since other configurations and operations are the same as those in the first embodiment, the same components are denoted by the same reference numerals and description thereof is omitted.

  FIG. 5A is a conventional example, and FIG. 5B is a schematic cross-sectional view of the developing device of this embodiment.

  In the developing device of this embodiment, the partition wall 7 is configured to have a triangular shape as shown in the cross section along the axial direction of the developing sleeve 8, and the bottom upper surface 7 a of the developing chamber 3 is transported with the developer in the developing chamber 3. It is characterized by being arranged so as to rise with respect to the direction.

  As a result, on the upstream side in the developing chamber transport direction, the developer that has risen due to the pressure from the stirring chamber can be quickly transported, and as a result, the developer surface on the upstream side of the developing chamber can be lowered.

  As described above, the upper surface 7 a of the partition wall 7 is provided so as to be inclined with respect to the developer conveyance direction in the developing chamber 3, whereby the first conveying screw 5 is provided in the developing chamber 3. Receives a conveying force on the side opposite to the conveying direction due to gravity. Further, since the end surface 7c on the downstream side in the developing chamber transport direction of the partition wall 7 is raised with respect to the sleeve 8, the developer surface TSd of the developer transported to the downstream side of the developing chamber is raised as compared with the conventional case, and The deviation of the developer distribution in the thrust is also reduced.

  Of course, also in the present embodiment, the first conveying screw 5 can be inclined along the upper surface 7 a of the partition wall 7 as in the second embodiment.

  Also in the developing device thus obtained, the deviation of the distribution of the developer amount in the developing device is reduced, and the developer is uniformly supplied to the developing sleeve 8 in the axial direction. It is possible to prevent the occurrence of image defects such as unevenness.

Example 4
6 and 7 show a fourth embodiment of the present invention.

  In the first embodiment, in the developing device in which one developing sleeve is arranged in the developing chamber, the partition wall 7 is inclined as a mechanism for controlling the developer surface and the developer amount distribution in the developing chamber 3 of the developer. The configuration is shown in the case of

  The present embodiment is characterized in that the partition wall 7 is inclined in the same manner as in the first embodiment with respect to a developing device in which two developing sleeves are arranged.

  In this embodiment, as shown in FIG. 6, two sleeves 8 a and 8 b are arranged substantially vertically in the developing container 2 so as to face the photosensitive drum 10. Since other configurations and operations are the same as those in the first embodiment, the same components are denoted by the same reference numerals and description thereof is omitted. However, in this embodiment, as shown in FIG. 6, the second conveying screw 6 rotates in a direction different from that of the first conveying screw 5, and the developer in the stirring chamber 4 is transferred to the first conveying screw. 5 is conveyed in the direction opposite to the conveying direction. Of course, the present embodiment is not limited to this configuration.

  FIG. 6 is a transverse sectional view showing a schematic configuration of the developing device of this embodiment, and FIG. 7 is a schematic longitudinal sectional view of the developing device.

  In this embodiment, the two sleeves 8 (8a, 8b) are provided substantially vertically, and the partition wall 7 partitioning the developing chamber 3 and the stirring chamber 4 is directed toward the developer transport direction in the developing chamber 3. It is characterized by being inclined so as to rise.

  The developing device of this embodiment is the type of the developing device shown in FIG. In this type of developing device 101, in FIG. 12, the amount of developer conveyed by the second conveying screw 106 in the stirring chamber 104 tends to gradually increase from the upstream end to the downstream end. . Therefore, the developer is supplied from the stirring chamber 104 to the lower developing sleeve 111 particularly in the direction of arrow A on the downstream end side, and the supply to the lower developing sleeve 111 is uneven. Due to the unevenness of supply to the developed lower sleeve 111, there is a possibility that an image defect such as a difference in density of an image formed in the sleeve axial direction may occur.

  That is, in the developing device 1 of the type of the present embodiment shown in FIG. 6, when the developer is displaced in the developing chamber 3 and the agitating chamber 4, the developer is supplied to the sleeve 8a due to the displacement on the developing chamber side. There arises a problem that the deviation occurs. In addition to this problem, the developer may be supplied from the stirring chamber 4 to the lower sleeve 8b in a portion where the developer surface in the stirring chamber is high, that is, on the downstream side of the stirring chamber conveyance path. As a result, the developer is excessively supplied to the lower sleeve only in that portion, resulting in density unevenness in the image and image defects.

  On the other hand, in the developing device 1 of the present embodiment, the partition wall 7 that partitions the developing chamber 3 and the stirring chamber 4 is provided so as to be inclined toward the developer conveying direction in the developing chamber 3. Deviation of the developer on the developing chamber side is suppressed. Further, as shown in FIG. 7B, on the stirring chamber 4 side, the partition wall 7 which is also a top plate is inclined so as to be lowered with respect to the transport direction. Therefore, the developer surface TSd on the downstream side of the stirring chamber. However, the partition wall 7 regulates the sleeve 8b to be lower than in the prior art (FIG. 7A). Therefore, the problem that the developer is supplied also from the stirring chamber 4 to the developing sleeve 8b is solved. As a result, the problem of excessive supply of developer in the sleeve 8b on the lower side, which is peculiar to this type of developing device by arranging the two sleeves 8a and 8b, is also suppressed.

  In order to enhance the effect of the developing device according to the present embodiment, the height position H1a of the developer surface TS with respect to the downstream end surface 81a of the developing sleeve 8a in the developer transport direction in the developing chamber 3 is the center of the sleeve 8a. It is preferable to be positioned above the line L1a. Further, the height position h1a of the partition wall 7 with respect to the end surface 81a of the developing sleeve 8a is located below the center line L1 of the sleeve 8a in FIG. 7B, but is located above the center line L1a of the sleeve 8a. More preferable results are obtained.

  Furthermore, as a means for enhancing the effect of the developing device according to the present embodiment, the height position H2b of the developer surface TS with respect to the downstream end surface 81b of the developing sleeve 8b in the developer transport direction in the stirring chamber 4 is the center of the sleeve 8b. It is preferable to be located below the line L1b. Furthermore, when the height position h2b of the partition wall 7 with respect to the downstream end surface 81b of the developing sleeve 8b is located below the center line L1b of the sleeve 8b, a more preferable result is obtained.

  Of course, also in the present embodiment, the first conveying screw 5 can be inclined along the upper surface 7a of the partition wall 7 as in the second embodiment. Similarly to the third embodiment, the partition wall 7 has a triangular configuration as shown in FIG. 5B, and the bottom upper surface 7a of the developing chamber 3 is inclined so as to rise in the developer transport direction in the developing chamber 3. It can also be made.

  In the developing device thus obtained, the deviation of the distribution of the developer amount in the developing device is reduced, and the developer is uniformly supplied to the developing sleeve 8 (8a, 8b) in the axial direction. Thus, it is possible to prevent the occurrence of image defects such as density unevenness. Furthermore, by regulating the developer surface in the stirring chamber 4, it is possible to prevent the occurrence of image defects such as density unevenness caused by excessive supply of the developer to the sleeve 8b.

1 is a schematic cross-sectional view of an embodiment of an image forming apparatus according to the present invention. 1 is a schematic cross-sectional view of an embodiment of a developing device according to the present invention. FIG. 3A is a schematic longitudinal sectional view of a conventional developing device, and FIG. 3B is a schematic longitudinal sectional view of an embodiment of the developing device according to the present invention. ) Is a perspective view of the developing sleeve. FIG. 4A is a schematic longitudinal sectional view of a conventional developing device, and FIG. 4B is a schematic longitudinal sectional view of another embodiment of the developing device according to the present invention. FIG. 5A is a schematic longitudinal sectional view of a conventional developing device, and FIG. 5B is a schematic longitudinal sectional view of another embodiment of the developing device according to the present invention. It is a typical cross-sectional view of another embodiment of the developing device according to the present invention. FIG. 7A is a schematic longitudinal sectional view of a conventional developing device, and FIG. 7B is a schematic longitudinal sectional view of another embodiment of the developing device according to the present invention. It is a typical cross-sectional view of a conventional developing device. It is a typical cross-sectional view of a conventional developing device. It is a typical longitudinal cross-sectional view of the conventional developing device. FIG. 10 is a schematic vertical and horizontal cross-sectional view of a conventional developing device. It is a typical cross-sectional view of a conventional developing device.

Explanation of symbols

1 (1Y, 1M, 1C, 1K) Developing device 2 Developing container 3 Developing chamber 4 Stirring chamber 5, 6 Conveying screw (conveying member)
7 Partition 8 Developer sleeve (developer carrier)
8a, 8b Two developing sleeves (developer carrier)
10 (10Y, 10M, 10C, 10K) Photosensitive drum (image carrier)
11, 12 opening (communication part)
21 (21Y, 21M, 21C, 21K) Primary charger (charging means)
22 (22Y, 22M, 22C, 22K) Light emitting element (latent image forming means)
23 (23Y, 23M, 23C, 23K) Transfer charger (transfer means)

Claims (14)

At least one rotatable developer carrying member for carrying and developing the developer to the development area;
A first chamber extending along a rotation axis direction of the developer carrying member and supplying a developer to the developer carrying member;
A second chamber disposed adjacent to and below the first chamber, and partitioned by a partition wall from the first chamber;
With
A first communication part and a second communication part for communicating the first chamber and the second chamber are provided in the vicinity of both ends of the partition wall in the rotation axis direction, respectively.
The developer conveying member provided in the first chamber and the second chamber conveys the developer from the second chamber to the first chamber via the first communicating portion, and the second communicating portion. In the developing device for circulating the developer between the first chamber and the second chamber by dropping the developer from the first chamber to the second chamber via
The developing device according to claim 1, wherein an upper surface portion of the partition wall serving as a bottom portion of the first chamber is provided to be inclined so as to rise in a developer transport direction in the first chamber.   The height of the developer surface at a position in the first chamber facing the downstream end of the developer carrying direction in the developer carrying maximum region in the rotation axis direction of the developer carrying body is determined by the developer carrying height. The developing device according to claim 1, wherein the developing device is located above a rotation axis of the body.   The height of the developer surface at a position in the second chamber facing the downstream end in the developer transport direction in the second chamber in the developer carrying maximum region in the rotation axis direction of the developer carrying member is The developing device according to claim 1, wherein the developing device is located below a rotation axis of the developer carrying member.   The height of the end of the upper surface of the partition wall on the downstream side in the developer transport direction in the first chamber is located above the rotation axis of the developer carrier. The developing device according to any one of the above items.   The height of the end of the lower surface of the partition wall on the downstream side in the developer transport direction in the second chamber is located below the rotation axis of the developer carrier. 5. The developing device according to any one of items 4.   The developing device according to claim 1, wherein an upper surface portion of the partition wall is disposed obliquely with respect to a rotation axis of the developer carrying member.   2. The partition wall is formed in a triangular shape in a cross section along a rotation axis direction of the developer carrying member, and an upper surface portion of the partition wall is disposed obliquely with respect to the developer carrying member. The developing device according to any one of items 5 to 5.   The developer carrying member includes an upper developer carrying member disposed in the vicinity of the first chamber and a lower developer bearing member disposed in the vicinity of the second chamber. The developing device according to claim 1.   The height of the developer surface at a position in the first chamber facing the downstream end of the developer transport direction in the first chamber in the developer carrying maximum region in the rotation axis direction of the upper developer carrier. The developing device according to claim 8, wherein the developing device is located above a rotation axis of the upper developer carrier.   The height of the developer surface at the position in the second chamber facing the downstream end of the developer conveyance direction in the second chamber in the developer carrying maximum region in the rotation axis direction of the lower developer carrying member. The developing device according to claim 8, wherein the developing device is located below a rotation axis of the lower developer carrying member.   The height of the end of the lower surface of the partition wall on the downstream side in the developer conveyance direction in the second chamber is located below the rotation axis of the lower developer carrier. Item 11. The developing device according to any one of Items 8 to 10.   The developing device according to claim 8, wherein an upper surface portion of the partition wall is disposed obliquely with respect to a rotation axis of the upper developer carrier.   The partition wall is formed in a triangular shape in a cross section along the rotation axis direction of the upper developer carrier, and an upper surface portion of the partition wall is disposed obliquely with respect to the developer carrier. Item 13. The developing device according to any one of Items 8 to 12. In an image forming apparatus comprising: an image carrier on which an electrostatic image is formed; and a developing device that develops the electrostatic image on the image carrier by applying a developer to a development region.
An image forming apparatus, wherein the developing device is the developing device according to claim 1.

Images